The present application relates generally to control systems for controlling the application of torque and/or force by an actuator and, more particularly, to control systems with adaptive parameter identification for electromechanical brake systems and the like.
Electromechanical brake systems have been developed for use in the automotive, aerospace and aeronautical industries to control the speed, stability and operation of various vehicles and devices. Electromechanical brake systems, commonly referred to as brake-by-wire systems, have been used in combination with, or in place of, conventional hydraulic brake systems.
A typical electromechanical brake system includes an electric motor adapted to advance an actuator into engagement with brake pads and/or a rotor, thereby generating a braking force. The amount of braking force generated typically is a function of the distal advancement of the actuator. Therefore, the braking force may be controlled by controlling the operation of the electric motor.
The braking force applied by an electromechanical brake system typically is controlled by monitoring the actual force exerted by the actuator or the relative position of the actuator and controlling the electric motor based upon the force and/or position signals to achieve the desired braking result. The force may be monitored directly using force gauges or the like, thereby providing a direct indication of the braking force. Alternatively, the position of the actuator may be monitored using various sensors (e.g., encoders, resolvers or Hall-Effect) such that the displacement of the actuator may be converted into a force signal by, for example, modeling the brake system as a spring and multiplying the piston displacement by a spring constant.
Control systems using direct force signals have exhibited slower response times and reduced performance due to filtering required to reduce the high signal to noise ratio. Furthermore, control systems using actuator displacement to determine force have presented disadvantages associated with parameter variation associated with temperature fluctuations, friction effects, wear and the like.
Accordingly, there is a need for an improved control system for controlling the application of force by an electromechanical actuator.